Are viruses alive?
Anyone with a cold or the flu virus feels as
if they are under attack by some organism. But in
the scientific community it's still an open-ended
question. This is why viruses do not belong to a
kingdom of living things. Just because a virus
seems alive doesn't mean it is alive. After all, it's
not even a single-celled organism. A virus is
little more than a strand of DNA or RNA covered
by a protein coating. Viruses are a thousand
times smaller than bacteria and come in a wide
range of shapes. Some look like weird, tall
spiders whereas others look like prickly
porcupine like soccer balls.
One thing is for sure; viruses are very much a part of life on Earth and the human
experience. Viruses infect animals, plants, and even bacteria. Humans are in a constant
battle with viruses. HIV (the virus that causes AIDS), the Ebola virus, and the West
Nile virus continue to make headlines and take millions of lives. Other maladies, such
as colds, the flu, chicken pox, measles, and hepatitis, are more common, but sometimes
just as deadly. Symptoms vary depending on which kind of cell is under attack. Cold
viruses attack the nose and throat, the rabies virus attacks the brain and nervous system,
and the human immunodeficiency virus (HIV) attacks white blood cells in the
bloodstream. Viruses can even cause some kinds of cancers and leukemia.
Live and Let Die
To determine whether a virus is alive or not, we could compare the virus's
characteristics to what many biologists consider the requirements of life. All living
things have several common characteristics. Some nonliving things may have one or
more of the characteristics but not all of them. For a virus then to be classified as alive it
must:
 Reproduce
 Obtain and use energy
 Grow, develop, and die
 Respond to the environment
Viruses do have DNA or RNA, and DNA is the code for life. Having genetic
material is an important step towards being classified as alive. DNA controls the
evolution of the cell and the organism. Like living things, viruses evolve through time
and thus can adapt to their environment. But unlike cells, viruses cannot use their
genetic material by themselves. They need a living cell in order to function and
reproduce; otherwise they are playing dead.
Resistance Is Futile
Because viruses are not cells, they can't divide by binary fission like bacteria. Yet
they do reproduce themselves in an extraordinary way. Their structure enables viruses
to attack a plant or animal cell called a HOST CELL. The protein shell protecting the
virus's DNA is covered with spike like protrusions. These spikes allow the virus to latch
onto the cells they infect. Once hooked on, the virus injects its genetic material into the
host cell. The virus's DNA takes control of the cell once it's within the cytoplasm and
begins to make the cell produce virus DNA and other parts of viruses. The host cell is
forced to expend all of its energy and resources to help the virus replicate and make
hundreds more viruses. The poor, weak cell usually bursts like an overinflated balloon
from all the viruses and is destroyed in the process. Then, the replicated virus attaches
itself to a new, unaffected host cell, and the viral infection continues.
Living things do more than just reproduce. They also must obtain food to fuel the
cell's metabolic activity. Some organisms, such as animals, eat other living things for
energy. Other organisms, such as plants, harness the Sun's energy to make their own
food. Because viruses aren't cells and have no activity within it, it has no need for food.
However, the virus-controlled host cell needs material and energy to reproduce the
viruses. Maybe viruses can fit the requirement that life forms need to obtain and use
energy.
All other living things also grow or get bigger. A virus does nothing inside its
protein coat; therefore it does not grow. But some scientists argue that a virus's growth
occurs inside the host cell where parts of viruses are built during reproduction.
Plants and animals react to the environment. All living things have ways of
sensing the world around them and can respond to changes in their environment. Do
viruses react? Viruses cannot move themselves, but there are some differences in
opinion that viruses do react to changes in the environment.
Remember, the virus's DNA or RNA can evolve over time, thereby increasing its
chances for survival and adapting to the environment. Like bacteria, they adapt through
genetic mutations caused by rapid reproduction. That is why it is so hard to cure viral
diseases. Viruses keep changing their DNA and protein coat to further their "life form"
and keep ahead of the game.
As humans, we like to classify things because it helps us understand the physical
world. Viruses must have a host cell to live and reproduce. Outside of the host cell,
viruses are pieces of genetic molecules that can do nothing by themselves. Viruses are
right on the border between living and nonliving. Some biologists currently see the
virus as a nonliving infectious particle. Other biologists disagree and suggest they are
alive because of what happens inside the host cell. Getting a definite answer if viruses
are alive or not may never happen. But hey, that's life.
1. List three words whose meaning you aren’t sure of.
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

2. Are viruses alive? List evidence from the article that viruses are alive and evidence that viruses
are not alive. List three of each.
Alive
Not Alive
1.
1.
2.
2.
3.
3.
3. What conclusion does the author come to concerning whether viruses are alive or not? Do you
agree with the author? Give evidence from the article to support your opinion.
1. List three words whose meaning you aren’t sure of.



2. Are viruses alive? List evidence from the article that viruses are alive and evidence that viruses
are not alive. List three of each.
Alive
Not Alive
4.
4.
5.
5.
6.
6.
3. What conclusion does the author come to concerning whether viruses are alive or not? Do you
agree with the author? Give evidence from the article to support your opinion.